Triaxial compressive behaviour of geotextile encased stone columns

A series of large-scale triaxial tests were performed on stone columns with and without geotextile encasement. Sixteen stone columns encased in four types of geotextiles and four ordinary stone columns with the size of 300 mm in diameter and 600 mm in height were tested under the confining pressures of 50, 100, 150 and 200 kPa. The results showed that the inclusion of geotextile encasement can be considered as a contribution to apparent cohesion or confining pressure of ordinary stone columns. The stress-strain relationship of encased stone columns was described as the superposition of a hyperbolic and a linear model, which were used to model the behaviour of triaxially loaded ordinary stone column and uniaxially loaded encased stone columns respectively. The model well captured the pre-failure behaviour of the encased stone columns.